Planetary gear mechanism for a bicycle

ABSTRACT

A planetary gear mechanism for a bicycle, and more particularly to a planetary gear mechanism comprising a first planetary mechanism connected coaxially in series to a second planetary mechanism, which second planetary mechanism is connected coaxially in series to a third planetary mechanism, the second planetary mechanism output is a step up in speed from the first planetary mechanism output, the third planetary mechanism output is a step up in speed from the second planetary mechanism output.

REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority from U.S. non-provisional patent application Ser. No. 12/660,861 filed Mar. 5, 2010.

FIELD OF THE INVENTION

The invention relates to a planetary gear mechanism for a bicycle, and more particularly to a planetary gear mechanism comprising a first planetary mechanism connected coaxially in series to a second planetary mechanism, which second planetary mechanism is connected coaxially in series to a third planetary mechanism, the second planetary mechanism output is a step up in speed from the first planetary mechanism output, the third planetary mechanism output is a step up in speed from the second planetary mechanism output.

BACKGROUND OF THE INVENTION

It is known that bicycles may have internal geared transmissions located in rear hubs. For example, the Shimano Company provides a Shimano Nexus™ eight speed transmission. The transmission comprises an internal geared planetary transmission which is located in a bicycle rear wheel hub. Rohloff GmbH of Germany provides a fourteen speed planetary gear transmission, also for use in a bicycle rear wheel hub.

The prior art transmissions have common disadvantages including heavy weight and that each is located in the bicycle rear wheel hub.

Also representative of the art is U.S. Pat. No. 6,468,178 (2002) to Mohtasham which discloses a rear wheel hub and chainless drive train gear assembly for use on a bicycle having an axle bracket fixed to the frame of the bicycle, a spindle extending axially through the axle bracket and left and right pedal crank arms for rotating the spindle upon application of a pedaling force. A primary drive gear fitted to the spindle drivingly engages carrier gears which operate a planet gear cage housing and a multiple planetary gear and sun gear arrangement according to various gear ratios determined by selective operation of a clutch assembly. Planetary gear groups each include an integral set of planetary gears of varying size which mesh with corresponding sun gear rings. Operation of the clutch assembly serves to selectively engage pawl stops with a corresponding sun gear ring, thereby engaging the corresponding sun gear ring with one of the planetary gears of the planetary gear groups according to a selected gear ratio. The planetary gear groups drive an annular gear ring and an associated annular needle bearing which, in a forward clockwise rotation, engages the hub body to rotate the rear bicycle wheel. Reverse rotation of the annular gear, in a counter-clockwise rotation, results in a freewheeling of the drive train gear assembly relative to the hub body.

What is needed is a planetary gear mechanism comprising a first planetary mechanism connected coaxially in series to a second planetary mechanism, which second planetary mechanism is connected coaxially in series to a third planetary mechanism, the second planetary mechanism output is a step up in speed from the first planetary mechanism output, the third planetary mechanism output is a step up in speed from the second planetary mechanism output. The present invention meets this need.

SUMMARY OF THE INVENTION

The primary aspect of the invention is to provide a planetary gear mechanism comprising a first planetary mechanism connected coaxially in series to a second planetary mechanism, which second planetary mechanism is connected coaxially in series to a third planetary mechanism, the second planetary mechanism output is a step up in speed from the first planetary mechanism output, the third planetary mechanism output is a step up in speed from the second planetary mechanism output.

Other aspects of the invention will be pointed out or made obvious by the following description of the invention and the accompanying drawings.

The invention comprises a planetary gear mechanism comprising an input member (22), a first carrier (100) having a first carrier first pinion gear (P1) and a first carrier second pinion gear (P2), each journalled to the first carrier, the first carrier rotationally fixed to the input member (22), the first carrier second pinion gear (P2) in meshing engagement with sun gear S1 which is engaged with a first brake (Brake 1), a second carrier (200) having second carrier first pinion gear (P4) and a second carrier second pinion gear (P5), each pinion gear (P4) and (P5) is journalled to the second carrier, the second carrier engaged with a second brake (Brake 2), a first ring gear (R1) in meshing engagement with the first carrier first pinion gear (P1), a second ring gear (R2) in meshing engagement with the second carrier first pinion gear (P4), the first ring gear and second ring gear comprise a ring gear member (400), a third carrier (300) having a third carrier first pinion gear (P6) and a third carrier second pinion gear (P7), each pinion gear (P6) and (P7) is journalled to the third carrier, a third ring gear (R3) in meshing engagement with the second carrier second pinion gear (P5), the third ring gear fixedly connected to the third carrier (300), a fourth ring gear (R4) engaged with a third brake (Brake 3) and in meshing engagement with the third carrier first pinion gear (P6), a first one-way clutch (CL1) engaged between the first carrier (100) and the ring gear member (400), a second one-way clutch (CL2) engaged between the second carrier (200) and the ring gear member (400), a third one-way clutch (CL3) engaged between the third carrier (300) and the fourth ring gear (R4), and an output member (44) in meshing engagement with the third carrier second pinion gear (P7).

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part of the specification, illustrate preferred embodiments of the present invention, and together with a description, serve to explain the principles of the invention.

FIG. 1 is a cross-sectional schematic view of the transmission.

FIG. 2 is a table of gear ratios.

FIG. 3 is a table of brake and clutch positions for each gear.

FIG. 4 is a partial side view of a bicycle.

FIG. 4A is a side view of a belt.

FIG. 5 is a cross-sectional view of the transmission.

FIG. 6 is a perspective view of a brake.

FIG. 7 is a cross-section at 7-7 in FIG. 5.

FIG. 8 is a cross-section at 8-8 in FIG. 5.

FIG. 9 is a cross-section at 9-9 in FIG. 5.

FIG. 10 is a cross-section at 10-10 in FIG. 5.

FIG. 11 is a cross-section at 11-11 in FIG. 5.

FIG. 12 is a cross-section at 12-12 in FIG. 5.

FIG. 13 is a cross-section at 13-13 in FIG. 5.

FIG. 14 is an exploded view of the transmission.

FIG. 15 is a detail of FIG. 14.

FIG. 16 is a detail of FIG. 14.

FIG. 17 is a detail of FIG. 14.

FIG. 18 is a detail of FIG. 14.

FIG. 19 is a detail of FIG. 14.

FIG. 20 is a detail of FIG. 14.

FIG. 21 is an end view of shift cam ring 600.

FIG. 22 is a side view of the shift cam ring 600.

FIG. 23 is an end view of shift cam ring 600.

FIG. 24 is a perspective view of shift cam ring 600.

FIG. 25 is an end view of shift cam ring.

FIG. 26 is a side view of the shift cam ring.

FIG. 27 is an end view of shift cam ring.

FIG. 28 is a perspective view of the shaft cam ring.

FIG. 29 is a perspective view of a shift dog.

FIG. 30 is a plan view of a shaft dog.

FIG. 31 is a side view of a shift dog.

FIG. 32 is a perspective view of a shift dog.

FIG. 33 is a perspective view of a shift dog.

FIG. 34 is a perspective view of a shift dog.

FIG. 35 is a perspective view of a shift dog.

FIG. 36 is a perspective view of a shift dog.

FIG. 37 is a detail of FIG. 18.

FIG. 38 is a detail of FIG. 19.

FIG. 39 is a detail of FIG. 19.

FIG. 40 is a detail of FIG. 6.

FIG. 41 is a detail of FIG. 6.

FIG. 42 is a detail of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 is a cross-sectional schematic view of the transmission. The invention generally comprises a planetary gear mechanism having an input member connected to a first planetary mechanism, the first planetary mechanism connected coaxially in series to a second planetary mechanism, which second planetary mechanism is connected coaxially in series to a third planetary mechanism, the second planetary mechanism output is a step up in speed from the first planetary mechanism output, the third planetary mechanism output is a step up in speed from the second planetary mechanism output, and the third planetary mechanism connected to an output member.

The proposed transmission is preferably located in a bicycle bottom bracket, see FIG. 4. Crank arms (see FIG. 4) are attached to each end of the input member 22. Carrier 100 is rigidly connected to the member 22, and thereby rotates with member 22. Carrier 100 further comprises a carrier pin or shaft 101.

Three planet pinion gears are journalled to pin 101, namely, P1, P2, P3. Each pinion gear P1, P2, P3 rotates together at the same speed about pin 101. Pinions P1, P2, P3 preferably comprise a single gear component having three different diameters, thereby describing gears P1, P2, P3.

Ring gear member 400 comprises a first ring gear R1 and a second ring gear R2. R1 is in meshing connection with pinion P1. Sun gears S1 and S2 are in meshing engagement with pinion gears P2 and P3 respectively. Sun gears S1 and S2 are reaction gears with brake 1 and brake 4. Brake 1 and brake 4 are connected to a bicycle frame (see FIG. 4). The rotational speed of pinion P1 is a function of whether brake 1 or brake 4 is engaged or disengaged, see FIG. 3.

Second planetary mechanism has two pinion gears P4 and P5 fixedly connected to a carrier shaft 201, and therefore gears P4 and P5 rotate together with shaft 201. Ring gear R2 is in meshing engagement with pinion gear P4. Carrier shaft 201 is journalled to carrier 200. Carrier 200 is a reaction member with and is engaged with brake 2.

A third ring gear R3 is fixedly attached to the input member of the third planetary mechanism which is carrier 300. The third planetary mechanism pinion gear P6 is in meshing engagement with fourth ring gear R4. Ring gear R4 is engaged with brake 3 and one-way clutch CL3. One-way clutch CL3 is engaged with carrier 300 and ring gear R3.

Pinion gear P6 and P7 are each journalled to carrier pin 301, and therefore rotate together. Pinion gears P6 and P7 preferably comprise a single gear component having two different diameters and hence define gears P6 and P7. Pinion gear P7 is in meshing engagement with output sun gear S3. Output sun gear S3 is fixedly attached to output sprocket 44.

All planetary carrier mechanisms are numbered as a function of increasing speed of their respective output members, that is, the third planetary mechanism causes rotation of sprocket 44, which in turn rotates faster than the relative rotation of the second planetary mechanism, which in turn rotates faster than the relative rotation of the first planetary mechanism when each planetary mechanism is operating with all one-way clutches dis-engaged, see FIG. 3 gear 12. Further, each planetary carrier mechanism is coaxial with the others and each of the planetary carrier mechanisms are connected in series.

Each planetary mechanism further comprises a one-way clutch, namely, CL1, CL2, CL3. When engaged each one-way clutch locks each respective planetary carrier mechanism with a gear ratio of 1:1.

A low-friction bushing 50 is disposed between input member 22 and sun gear S1. A low-friction bushing 51 is disposed between sun gear S1 and sun gear S2. A low-friction bushing 52 is disposed between sun gear S3 and input member 22.

For ease of reference, the following assemblies may also be generally referred to as the first planetary mechanism, second planetary mechanism and third planetary mechanism.

-   -   First planetary mechanism: carrier 100; pinion gears P1, P2, P3;         shaft 101; one-way clutch CL1; ring gear R1     -   Second planetary mechanism: carrier 200; pinion gears P4, P5;         shaft 201; one-way clutch CL2; ring gear R2; ring gear R3     -   Third planetary mechanism: carrier 300; pinion gears P6, P7;         shaft 301; one-way clutch CL3; ring gear R4

FIG. 2 is a table of gear ratios. Planetary mechanism (carrier) 100 has gear ratios 1, 1.33, and 1.76. Planetary mechanism 200 has gear ratios 1 and 1.15. Planetary mechanism 300 has gear ratios 1 and 2.30. The combined overall gear ratio is noted in column i.

The inventive transmission results in very linear steps between each gear ratio averaging approximately 15%. This allows predictable power requirements for each shift as a rider shifts up and down through the gears.

Since the inventive transmission increases the speed of the output member front sprocket 44 compared to the speed of input member 22, the ratio between the front sprocket 44 and a rear sprocket 36 installed on the rear wheel 34 is adjusted accordingly. Hence, for example, front sprocket 44 has 32 teeth and the rear sprocket has 42 teeth. The number of teeth on the front sprocket and rear sprocket may be adjusted as may be required by a user.

FIG. 3 is a table of brake and clutch positions for each gear. For example, first gear, the slowest gear, has all planetary mechanisms 100, 200, 300 at gear ratio 1:1 and all clutches CL1, CL2, CL3, are locked. In first gear all brakes 1, 2, 3, 4 are disengaged.

The inventive transmission is about 20%-30% lighter than prior art transmissions. Another advantage of the transmission is better clearance in a bicycle frame since front sprocket is much smaller.

The following is provided as an example and is not intended to limit the design parameters which may be used for each component. The diameters are in mm.

Pinion Gear Ring Gear Diameter No. of Teeth P1 NA 13.6 17 P2 NA 18.4 23 P3 NA 10.4 13 P4 NA 11.2 14 P5 NA 13.6 17 P6 NA 16 20 P7 NA 10.4 13 NA R1 57.6 72 NA R2 45.6 57 NA R3 48 60 NA R4 52.8 66

FIG. 4 is a partial side view of a bicycle. The inventive transmission will be preferably installed in bottom bracket 20. Crank arms 41 are connected to input member 22. A rider's feet engage pedals 42. A flexible drive member 50 is engaged between sprocket 44 and rear sprocket 36. Rear sprocket 36 is connected to wheel 34. A rider (not shown) sits on seat 24. Wheel 34, crank arms 41, bottom bracket 20, seat 24 are connected to bicycle frame 30, known in the art. Flexible drive member 50 may comprise a belt or chain.

FIG. 4A is a side view of a belt. Belt 50 comprises a body 98. Teeth 99 extend from belt body 98. Teeth 99 extend across the width of the belt and normal to a longitudinal or endless direction. This style of belt is also referred to as a toothed, cogged or synchronous belt as is known in the automotive arts.

FIG. 5 is a cross-sectional view of the transmission. Planetary carrier mechanisms 100, 200, 300 are shown connected in series within bottom bracket or a transmission housing 20. Carrier 100 is fixedly connected to input member 22. Carrier 200 is rotatable about member 22 on bearings 1002, 1003. Carrier 300 is rotatable about member 22 on bearings 1003, 1004, 1005. Member 22 rotates within bottom bracket 22 on bearing 1001. Member 22 may be hollow to reduce weight of the transmission.

FIG. 6 is a perspective view of a brake. The figure shows sun gears S1 and S2. Brake 1 engages sun gear S1. Brake 4 engages sun gear S2. The brake mechanisms for shifting the planetary transmission ensures that a compound planetary set cannot engage two gear sets at once and thus become locked. The proposed mechanism is located in the proximity of the sun gears of a compound planetary gear set but could easily be applied to breaking or shifting of a compound planetary gear set with multiple ring gears.

The mechanism comprises two levers (701,702) (801,802) configured in a manner such that one physically interferes or prohibits the other lever from engaging its sun gear while the other is engaged with its respective sun gear. When one sun gear is stopped by a brake, the other sun gear will be forced to rotate relative to the stopped sun gear. In the case of a compound set with more than two sun gears, each sun gear will rotate at a different speed than the others. However, if each brake is applied to each sun at the same time the transmission would lock and not rotate. Each lever limits the rotation or brakes their respective sun gear by engaging with a stepped area of the sun gear such that the lever engages the face of a step and limits the rotation of the sun in one direction. The mechanism could engage the sun gears from radially outside or radially inside depending on the configuration required.

The shift levers are actuated by a roller 601 that engages a profiled surface 601B. As the profile changes, the levers are moved to either engage as a brake or open and allow free movement of the respective sun gear.

Each brake 1 and brake 4 comprises a shift member 701 and 801 respectively. Shift cam 600 engages shift rollers 601. Each shift roller 601 engages a compliant pad or member 602.

Each shift member 701 and 801 are pivotally mounted to end cap 205. Each end 702, 802 of each shift member 701, 801 engages sun gear teeth 210, 211 respectively.

In operation, shift cam 600 rotates enabling each shift roller 601 to move radially outward, thereby releasing each complaint pad 602. Releasing each complaint pad 602 enables each shift member 701, 801 to pivot due to the biasing caused by springs 7001 thereby causing shift members 701, 801 to engage sun gear teeth 210, 211 respectively. Engagement of each shift member 701, 801 with the respective sun gear teeth stops rotation of the respective sun gear in a clockwise direction CW.

The reaction force caused by engagement of the shift members 701, 801 with teeth 210, 211 is transmitted through each shift member 701, 801 to the end cap 205 and thereby to the bicycle frame.

Brake 2 and brake 3 are identical in description and operation to brake 1 and brake 4.

FIG. 7 is a cross-section at 7-7 in FIG. 5. Pinion gear P7 has a meshing engagement with sun gear S3. Brake 3 shift member 601 engages teeth 213. Teeth 213 are disposed on an outer perimeter of ring gear R4. In the instant embodiment there are three sets of pinion gears P6, P7.

FIG. 8 is a cross-section at 8-8 in FIG. 5. Pinion gear P6 is journalled to pin 301.

FIG. 9 is a cross-section at 9-9 in FIG. 5. Pinion gear P5 is journalled to pin 201. Pinion gear P5 has a meshing engagement with ring gear R3. Brake 2 comprises shift member 901 which engages teeth 212. Teeth 212 are disposed on an outer perimeter of carrier 200. In the instant embodiment there are three sets of pinion gears P4, P5.

FIG. 10 is a cross-section at 10-10 in FIG. 5. Pinion gear P4 has a meshing engagement with ring gear R2.

FIG. 11 is a cross-section at 11-11 in FIG. 5. Pinion gear 1 and P2 are journalled to pin 101. Pinion gear P1 has a meshing engagement with ring gear R1. In the instant embodiment there are four sets of pinion gears P1, P2, P3, each journalled to a pin 101.

FIG. 12 is a cross-section at 12-12 in FIG. 5. Sun gear S1 has a meshing engagement with pinion gear P2. Sun gear S2 has a meshing engagement with pinion gear P3.

FIG. 13 is a cross-section at 13-13 in FIG. 5. Pinion gear P3 has a meshing engagement with sun gear S2.

FIG. 14 is an exploded view of the transmission. Axis A-A is the axis of rotation. A belt engages sprocket 44 and a rear hub, see FIG. 4.

Transmission case 20 may be inserted into a bottom bracket in a cartridge manner. Namely, case 20 is inserted into a cylindrical receiver, the cylindrical receiver comprising the bottom bracket. In an alternate embodiment, the seat stay, seat tube and chain stays can be attached directly to case 20, for example by welding, thereby making the transmission case 20 the bottom bracket. The internals for the transmission would not be changed for either embodiment. FIG. 15 is a detail of FIG. 14. Shift cables 1, 2 (known in the art) are connected to the transmission through adjusting grommets 81 and 82 respectively. Shift cables 1, 2 are typically connected to shift mechanisms on a bicycle handlebar for example (not shown). Grommets 81, 82 are threadably engaged with case 20 at hole 21, 22 respectively. Bearing 1006 is disposed between sun gear S3 and case 20.

Sprocket 44 comprises holes 440 which receive belt teeth (not shown). Further, holes 440 allow dirt and debris thrown up by the wheels to drop through the sprocket, thereby allowing the sprocket to be self cleaning. This prevents debris from accumulating between the belt and the sprocket which would otherwise hinder performance.

Bushings 1007 and 1008 engage bearings 1005 and 1006 respectively.

Spacer 800 is disposed between bearing 1004 and bearing 1003. Spacer 801 is disposed between bearing 1003 and bearing 1002.

Nuts 42 attach sprocket 41 to a spider 51 on sun gear S3.

FIG. 16 is a detail of FIG. 14. Each cable 1, 2 is fastened to receiver 206. Receiver 206 is fixed to an end of shift cam ring 600. By extending or retracting each cable 1, 2 the shift cam ring is thereby rotated within the transmission case 20. The range of rotational movement of shift cam ring 600 is approximately 130°.

Surface 601A engages roller 603 which engages shift dog 702A and 802A. Surface 602A engages roller 603 which engages compliant member 601 and thereby shift dog 720, 721. Surface 603A engages roller 603 which engages shift dog 702B, 802B. Surface 601B engages roller 603 which engages shift dogs 820, 821.

Shift dogs 720 and 721 engage teeth 212. Shift dogs 820, 821 engage teeth 213.

Springs 8001A, 8001B, 8001C, 8001D bias each shift dog 720, 721, 820, 821 into engagement with teeth 212, 213 respectively. Biasing the shift dogs causes the rollers 603 to maintain contact with cam surfaces 601A, 602A, 603A and 601B.

FIG. 17 is a detail of FIG. 14. Bushing 1010 engages bearing 1002. Shift dogs 701A, 801A engage teeth 211. Shift dogs 701B, 801B engage teeth 210.

FIG. 18 is a detail of FIG. 14. FIG. 19 is a detail of FIG. 14. FIG. 20 is a detail of FIG. 14. Threaded ring 23 attaches end 205 to case 20. Bushing 1009 engages bearing 1001. Cap 43 retains crank arms (not shown) to axle shaft 22.

Springs 7001A, 7001B, 7001C, 7001D bias each shift dog 701A, 801A, 701B, 801B into engagement with teeth 211, 210 respectively.

FIG. 21 is an end view of shift cam ring 600. Shift cam ring 600 comprises member 600A and 600B for ease of manufacture and assembly. Member 600A is cylindrical. Shift cam ring 600 is disposed in the transmission and is radially outermost from the planetary gear sets 100, 200, 300 and within the transmission case 20, see FIG. 5.

FIG. 22 is a side view of the shift cam ring 600. Member 600A is shown having a lattice structure in order to reduce weight while maintaining strength. Shift cam ring 600 is rotatable within transmission case 20.

FIG. 23 is an end view of shift cam ring 600.

FIG. 24 is a perspective view of shift cam ring 600. Each shift circumferential surface 601A and 602A is disposed at opposite ends of member 600A. Each surface 601A and 602A comprises a radially inward surface of the shift cam ring 600.

Circumferential surface 601A comprises a plurality of features each having a differing slope or radius. A radial position of rollers 603 engaging compliant member 601 thereby shift dog 702A and 802A is each determined according to which surface of 601A is engaging rollers 603.

Circumferential surface 602A comprises a plurality of features each having a differing slope or radius. A radial position of rollers 603 engaging compliant member 601 and thereby shift dog 720 and 721 is each determined according to which surface of 602A is engaging rollers 603.

Circumferential surface 603A comprises a plurality of features each having a differing slope or radius. A radial position of rollers 603 engaging compliant member 601 and thereby shift dog 702B and 802B is each determined according to which surface of 603A is rollers 603.

Circumferential surface 601B comprises a plurality of features each having a differing slope or radius. A radial position of rollers 603 engaging compliant member 601 and thereby shift dog 820 and 821 is each determined according to which surface of 601B is engaging rollers 603. 602. Each surface 603A and 601B comprises a radially inward surface of the shift cam ring 600.

FIG. 25 is an end view of shift cam ring. Shift cam ring 600 comprises member 600A and 600B for ease of manufacture and assembly. Member 600B is cylindrical.

Shift cam ring 600 is disposed in the transmission outermost from the planetary gear sets and within the transmission case 20, see FIG. 5. The transmission is shifted by rotation of the shift cam ring 600 through extension and retraction of shift cables 1, 2 see FIG. 14.

FIG. 26 is a side view of the shift cam ring.

FIG. 27 is an end view of shift cam ring.

FIG. 28 is a perspective view of the shaft cam ring. Member 600B comprises extended members 601B and 602B. each member 601B and 602B engages a cooperating portion of 600A, namely, slots 603A and 604A.

FIG. 29 is a perspective view of a shift dog. Portion 7002 receives member 601. Member 601 comprises a resilient material which can be compressed and will rebound when the compression is released.

Each shift dog 701, 801 and 702, 802 is identical to the others. For each shift dog 702, 802 a member 602 is fixed to portion 7002.

FIG. 30 is a plan view of a shift dog. Receiving portion 760 receives a member 601. Each shift dog 720, 820, 721, 821 is identical to the others. For each shift dog 720, 820, 721 and 821 a member 602 is fixed to portion 760.

FIG. 31 is a side view of a shift dog. Receiving portion 760 receives a member 601.

FIG. 32 is a perspective view of a shift dog. Shift dog 820 is pivotally mounted to a dog mount 840. Dog mount 840 is fastened to case 20 (not shown). A roller 603 is disposed between surface 601B and member 601.

FIG. 33 is a perspective view of a shift dog. Spring 8001A biases shift dog 820 toward teeth 213.

FIG. 34 is a perspective view of a shift dog. Shift dog 840 is fastened to case 20.

FIG. 35 is a perspective view of a shift dog. Shift dog 720 is pivotally mounted to dog mount 740. Spring 8001A biases shift dog 720 toward teeth 212. A roller 603 is disposed between a surface 602A and a member 601.

FIG. 36 is a perspective view of a shift dog. Dog mount 740 is fastened to case 20.

FIG. 37 is a detail of FIG. 18. One way clutch dog 920 is pivotally mounted to carrier 300. Spring 921 biases one way clutch dog 920 against teeth 213 of ring gear R4. One way clutch dog 920 allows a reverse rotational movement of ring gear R4 by disengaging teeth 213. Depending upon the particular gear that is engaged, the one way clutch is the “free wheel” feature of the transmission which allows a rider to stop pedaling and coast. A second identical one way clutch dog is disposed opposite that shown in FIG. 37, thereby forming a pair of one way clutch shift dogs.

FIG. 38 is a detail of FIG. 19. One way clutch dog 930 is pivotally mounted to carrier 200. Spring 931 biases one way clutch dog 930 against teeth 401 of ring gear R1. One way clutch dog 930 prevents a reverse rotational movement of ring gear R1 by engaging teeth 401. One way clutch dog 930 allows a forward rotational movement of ring gear R1 relative to carrier 200 by disengaging from teeth 401. Depending upon the particular gear that is engaged, the one way clutch is the “free wheel” feature of the transmission which allows a rider to stop pedaling and coast. A second identical one way clutch dog is disposed opposite that shown in FIG. 38, thereby forming a pair of one way clutch shift dogs.

FIG. 39 is a detail of FIG. 19. One way clutch dog 901 is pivotally mounted to carrier 100. Spring 902 biases one way clutch dog 901 against teeth 401 of ring gear R1. One way clutch dog 901 allows forward rotational movement of ring gear R1 relative to carrier 100 by disengaging teeth 401. One way clutch dog 901 prevents a reverse rotational movement of ring gear R1 by engaging teeth 401. Depending upon the particular gear that is engaged, the one way clutch is the “free wheel” feature of the transmission which allows a rider to stop pedaling and coast. A second, identical one way clutch dog is disposed opposite that shown in FIG. 39, thereby forming a pair of one way clutch shift dogs.

FIG. 40 is a detail of FIG. 6. Roller 603 engages surface 601A, thereby pressing upon member 602 which in turn presses shift dog 701, thereby disengaging shift dog 702 from teeth 210.

Use of resilient member 602 allows the shift cams to rotate while the shift dog is still engaged with the teeth. The cams can rotate and compress the resilient member while the dog is engaged with the teeth and compressively loaded. When a bicycle rider pedals a bicycle, the torque input into the transmission is cyclic as the input shifts from one pedal to the other. Even for the very best cyclists, the input torque drops to zero or near zero during this transfer of input from one pedal the other. Due to the cyclic input loading of a pedaling bicycle rider, when the torque momentarily approaches or reaches zero, the force on the shift dog/tooth interface also drops to zero or near zero, it is at this moment that the shift dog will rotate out of engagement due to the resilient member's desire to return to a relaxed state. This gives the rider the impression of being able to shift under load while in actuality the shift occurs under near no load conditions.

A duplicate set of shift dogs as described in this FIG. 38 are likewise mounted in area “A”. All shift dogs 701, 702, 801, 802 are pivotally mounted to member 205 at mounting portions 2051, 2052, 2053, 2054 respectively.

FIG. 41 is a detail of FIG. 6. Shift dog 701 is allowed to move radially outward by a movement of roller 601, which roller follows surface 601A as surface 601A is rotated during a shift by a rider. Shift dog 702 is shown fully engaged with teeth 210. Shift dog 701 cooperatively engages protrusion 803, which in turn allows shift dog 702 to pivot and thereby engage teeth 210. Spring 7001A urges shift dog 801 into engagement with roller 601, and thereby said roller 601 into surface 601A. Shift dogs 802 and 702 are able to pivot independently of each other, but because of the cooperative arrangement of protrusion 803 and shift dog 701, they cannot both engage with the teeth of their respective sun gears at the same time. If shift dog 702 is engaged with teeth 210, then the relation of protrusion 803 and shift dog 701 prevents shift dog 802 from engaging teeth 211. Conversely, if shift dog 802 is engaged with teeth 211, shift dog 702 cannot pivot to engage with teeth 210.

FIG. 42 is a detail of FIG. 6. Since shift dog 701 is fully pressed by roller 603, shift dog 702 is fully disengaged from teeth 210. Shift dog 701 cooperatively engages protrusion 803, which in turn prevents shift dog 702 from pivoting to engage teeth 210. Protrusion 803 is positioned radially above shift dog 701. If shift dog 701 rotates to engage teeth 210, shift dog 802 is held out of engagement with teeth 211 as shown in FIG. 39. Shift dog 802 is prevented from engaging teeth 211 by the cooperative arrangement of protrusion 803 and shift dog 701.

When shift dog 802 is engaged with teeth 211 as shown in FIG. 40 shift dog 702 is prevented from engaging teeth 210 by the arrangement of protrusion 803 and shift dog 701. Both shift dogs 702 and 802 can be disengaged from teeth 210 and 211 simultaneously. Shift dogs 702, 802 are prevented from engaging the teeth simultaneously by the cooperative arrangement of protrusion 803 and shift dog 701. Each protrusion 703, 803 is identical to the other. Protrusion 703 extends from the end of shift dog 701. Protrusion 803 extends from the end of shift dog 801.

Although a form of the invention has been described herein, it will be obvious to those skilled in the art that variations may be made in the construction and relation of parts without departing from the spirit and scope of the invention described herein. 

We claim:
 1. A bicycle comprising: a frame (30); a planetary gear transmission comprising an input member (22), a first planetary mechanism, a second planetary mechanism and a third planetary mechanism, and an output member (44); the first planetary mechanism, second planetary mechanism and third planetary mechanism are each connected in series; and a flexible drive member (50) drivingly engaged between the output member (44) and a wheel (34).
 2. The bicycle as in claim 1, wherein: the input member is connected to the first planetary mechanism; the second planetary mechanism rotary output is a step up in speed from the first planetary mechanism rotary output, the third planetary mechanism rotary output is a step up in speed from the second planetary mechanism rotary output; and the third planetary mechanism is connected to the output member.
 3. A bicycle comprising: a frame having a bottom bracket; a planetary gear transmission comprising an input member, a first planetary mechanism, a second planetary mechanism and a third planetary mechanism, and an output member, the first planetary mechanism, second planetary mechanism and third planetary mechanism are each connected in series; the planetary gear transmission disposed in the bottom bracket; and a flexible drive member drivingly engaged between the output member and a rear wheel.
 4. The bicycle as in claim 3, wherein the planetary gear transmission comprises twelve output gear ratios.
 5. The bicycle as in claim 3, wherein the flexible drive member comprises a belt.
 6. The bicycle as in claim 3, wherein the input member comprises a crank.
 7. The bicycle as in claim 5, wherein the output member comprises a sprocket, the sprocket having a plurality of holes, each hole being engagable by a belt tooth. 